Beverage, shampoo, rinse, paint and the like must be given some viscosity in order to facilitate dispensing from containers or spreading on use. To this end, water-soluble cellulose ethers such as alkyl celluloses and hydroxyalkyl alkyl celluloses are often added as the thickener. Also an aqueous solution of cellulose ether must be prepared to form a surface coating for facilitating granulation or hiding the bitterness of pharmaceutical or other preparations, or imparting thickness to food or beverage.
If cellulose ether in powder form is directly admitted into cold water, particle surfaces are immediately dissolved to become viscous, and particles attract each other and agglomerate together, forming agglomerates having a size from rice grains to adzuki beans, known as “clumps” or “lumps”. The surface of “clumps” is a coating having a high viscosity, which becomes a barrier against further penetration of water. It will take at least one day until complete dissolution.
Patent Document 1 discloses to add or spray 2 to 20 parts by weight of a glycol and/or nonionic surfactant having a HLB of 3 to 17 to 100 parts by weight of cellulose ether.
In Patent Document 1, however, when it is desired to prepare an aqueous solution having a concentration of at least 2% by weight, clumps or lumps are likely to form. This problem may be overcome by treatment with a large amount of surfactant solution, but another problem arises. Since surfaces of cellulose ether particles become readily dissolvable, these particles agglomerate together to form large agglomerates. The dissolution rate in cold water is significantly retarded.
Patent Document 2 discloses a cold pack for food which is prepared by attaching a safe food additive, tannin to cellulose ether so as to be water-insoluble, and adding another food additive such as sodium hydrogencarbonate or sodium carbonate thereto so that the cellulose ether is water-soluble.
In Patent Document 2, more tannin must be attached for further improvement in dissolution. The more amount of tannin can add to bitterness when a significant amount of cellulose ether is used as a sizing agent, thickener or binder.